Gallid herpesvirus 1
Encyclopedia
Gallid herpesvirus 1 (also known as Avian herpesvirus 1) is a virus
of the family Herpesviridae
that causes avian infectious laryngotracheitis. It was originally recognized as a disease of chicken
s in the United States in 1926. The disease also occurs in pheasant
s.
The disease is usually referred to as Infectious laryngotracheitis or simply LT in the poultry industry. It is widely viewed as one of the most contagious viruses that affect the poultry industry. A confirmed case will usually result in the establishment of a quarantine zone around the farm. Inside this quarantine zone, poultry workers will avoid poultry farms to prevent the spread of the virus.
GaHV-1 is shed in respiratory secretions and transmitted by droplet inhalation or via fomite
s. A previously unexposed flock will develop cases for two to eight weeks following introduction. The incubation period
is two to eight days.
and trachea
. A diphtheritic membrane may form in the trachea, causing obstruction.
There may be problems in egg laying and the production of abnormal or thin-shelled eggs.
Mortality is typically less than 15 percent.
Histopathology
, PCR, ELISA
, immunofluorescent
staining and viral isolation are all possible methods of diagnosis.
Biosecurity
measure including quarantine
, isolation
and disinfection
are very important in controlling the spread of an outbreak.
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
of the family Herpesviridae
Herpesviridae
The Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein , referring to the latent, recurring infections typical of this group of viruses...
that causes avian infectious laryngotracheitis. It was originally recognized as a disease of chicken
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
s in the United States in 1926. The disease also occurs in pheasant
Pheasant
Pheasants refer to some members of the Phasianinae subfamily of Phasianidae in the order Galliformes.Pheasants are characterised by strong sexual dimorphism, males being highly ornate with bright colours and adornments such as wattles and long tails. Males are usually larger than females and have...
s.
The disease is usually referred to as Infectious laryngotracheitis or simply LT in the poultry industry. It is widely viewed as one of the most contagious viruses that affect the poultry industry. A confirmed case will usually result in the establishment of a quarantine zone around the farm. Inside this quarantine zone, poultry workers will avoid poultry farms to prevent the spread of the virus.
GaHV-1 is shed in respiratory secretions and transmitted by droplet inhalation or via fomite
Fomite
A fomite is any inanimate object or substance capable of carrying infectious organisms and hence transferring them from one individual to another. A fomite can be anything...
s. A previously unexposed flock will develop cases for two to eight weeks following introduction. The incubation period
Incubation period
Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical or radiation, and when symptoms and signs are first apparent...
is two to eight days.
Clinical signs and diagnosis
Symptoms include coughing, sneezing, head shaking, lethargy, discharge from the eyes and nostrils (sometimes bloody), and difficulty breathing. The name comes from the severe inflammation of the larynxLarynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
and trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
. A diphtheritic membrane may form in the trachea, causing obstruction.
There may be problems in egg laying and the production of abnormal or thin-shelled eggs.
Mortality is typically less than 15 percent.
Histopathology
Histopathology
Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease...
, PCR, ELISA
ELISA
Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...
, immunofluorescent
Immunofluorescence
Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on biological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows...
staining and viral isolation are all possible methods of diagnosis.
Treatment and control
A vaccine is available (ATCvet code: ), but it does not prevent latent infections. It can be used during an outbreak to decrease morbidity and deaths.Biosecurity
Biosecurity
Biosecurity is a set of preventive measures designed to reduce the risk of transmission of infectious diseases, quarantined pests, invasive alien species, living modified organisms...
measure including quarantine
Quarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....
, isolation
Isolation (health care)
In health care, isolation refers to various measures taken to prevent contagious diseases from being spread from a patient to other patients, health care workers, and visitors, or from others to a particular patient...
and disinfection
Disinfection
Disinfectants are substances that are applied to non-living objects to destroy microorganisms that are living on the objects. Disinfection does not necessarily kill all microorganisms, especially nonresistant bacterial spores; it is less effective than sterilisation, which is an extreme physical...
are very important in controlling the spread of an outbreak.
External links
- Avian Infectious Laryngotracheitis, expert reviewed and published by WikiVetWikiVetWikiVet is a wiki of veterinary content, run using the MediaWiki software. The project is a collaborative initiative involving UK veterinary schools with external support...
, accessed 07/10/2011 - Virus Pathogen Database and Analysis Resource (ViPR): Herpesviridae